Advanced Computer Architecture Ranjit Patnaik, Assistant Professor Department Of Computer Science and Engineering, Gandhi Institute of Engineering and Technology, GUNUPUR July 26,2017
Chapter 1 Microprocessor 1.1 Introduction 126.96.36.199.1 Microprocessor is a controlling unit of a micro-computer, fabricated on a small chip capable of performing ALU (Arithmetic Logical Unit) operations and communicating with the other devices connected to it. Microprocessor consists of an ALU, register array, and a control unit. ALU performs arithmetical and logical operations on the data received from the memory or an input device. Register array consists of registers identified by letters like B, C, D, E, H, L and accumulator. The control unit controls the flow of data and instructions within the computer. Figure 1.1: Block Diagram of Microprocessor. 1.2 How does a Microprocessor Work? 188.8.131.52.1 The microprocessor follows a sequence: Fetch, Decode, and then Execute.Initially, the instructions are stored in the memory in a sequential order. The microprocessor fetches those instructions from the memory, then decodes it and executes those instructions till STOP instruction is reached. Later, it sends the result in binary to the output port. Between these processes, the register stores the temporarily data and 1
2 CHAPTER 1. MICROPROCESSOR ALU performs the computing functions. Here is a list of some of the frequently used terms in a microprocessor : 1. Instruction Set : stand. It is the set of instructions that the microprocessor can under- 2. Bandwidth : It is the number of bits processed in a single instruction. 3. Clock Speed : It determines the number of operations per second the processor can perform. It is expressed in megahertz (MHz) or gigahertz (GHz).It is also known as Clock Rate. 4. Word Length : It depends upon the width of internal data bus, registers, ALU, etc. An 8-bit microprocessor can process 8-bit data at a time. The word length ranges from 4 bits to 64 bits depending upon the type of the microcomputer. 5. Data Types : The microprocessor has multiple data type formats like binary, BCD, ASCII, signed and unsigned numbers. 1.3 A microprocessor can be classified into three categories : The microprocessors are categorised into three types such as: • RISC Processors • CISC Processors • Special Processors Figure 1.2: Categories of Microprocessor.
1.3. A MICROPROCESSOR CAN BE CLASSIFIED INTO THREE CATEGORIES : 3 1.3.1 RISC Processors 184.108.40.206.1 RISC stands for Reduced Instruction Set Computer. It is designed to reduce the execution time by simplifying the instruction set of the computer. Using RISC processors, each instruction requires only one clock cycle to execute results in uniform execution time. This reduces the efficiency as there are more lines of code, hence more RAM is needed to store the instructions. The compiler also has to work more to convert high-level language instructions into machine code. Some of the RISC processors are ? • Power PC: 601, 604, 615, 620 • DEC Alpha: 210642, 211066, 21068, 21164 • MIPS: TS (R10000) RISC Processor • PA-RISC: HP 7100LC 220.127.116.11 Architecture of RISC 18.104.22.168.1 RISC microprocessor architecture uses highly-optimized set of instructions. It is used in portable devices like Apple iPod due to its power efficiency. Figure 1.3: RISC Archutecture 22.214.171.124 126.96.36.199.1 Characteristics of RISC The major characteristics of a RISC processor are as follows: • It consists of simple instructions.